Reaction products of fatty acid derivatives and alkanol mono- or polyamines are known to be useful additives for application in gasoline and diesel fuel.
Chapter 7: Organic Friction Modifiers, Lubricant Additives: Chemistry and Applications; Leslie R. Rudnick, CRC 2003, ISBN 0824708571. Kenbeek and Buenemann explain that non-acetic organic friction modifiers are preferably long straight-chain molecules with small polar heads. They are described to form adsorption layers on the surface where multiple molecules are adsorbed by hydrogen bonding and Debye orientation forces. Van der Waals forces cause the molecules to align themselves such that they form multimolecular clusters that are parallel to each other. Examples of organic friction modifiers are oleylamide and glycerol mono-oleate (GMO).
EP-A-1 295 933 describes deposit control additives for direct injected engines available by reaction of monocarboxylic acids and polyamines. Most preferred is a molar ratio of 1 to 1.5 moles of monocarboxylic acid and 1 mole of polyamine. Specific preferred examples are the reaction products of equimolar amounts of tallow fatty acid or oleic acid and AEAE. According to the general procedure disclosed therein the reaction is performed at reflux temperature which is in the range of 150 to 175° C. There is no suggestion made in said document with respect to choosing the reaction conditions (molar ratio and/or reaction temperature) such that polysubstituted alkanolamines are preferentially formed. In particular, it is not suggested to control the kinetics of the reaction by selecting a suitable temperature profile.
Furthermore, there is no disclosure in EP-A-1 295 933 of benefits in terms of improving the fuel economy of internal combustion engines by use of functional fluid compositions whether fuel compositions as fuel for the engine, or lubricating oil compositions for lubricating the engine, which fluid compositions incorporate the product of the reaction of monocarboxylic acids and polyamines.
EP-A-1 435 386 describes fatty acid alkanol amides, which improve the acceleration properties of internal combustion engines. This document describes alkanol monoamides obtainable by reaction of equimolar quantities of a fatty acid or its ester and of an alkanol monoamine.
Improved acceleration response is exemplified for gasoline fuels containing these compounds. Further benefits in terms of increased fuel efficiency, stability of engine rotation during idling and decrease in vibration of the engine and noise are also stated in the description of EP-A-1 435 386, but such additional benefits are not exemplified therein.
EP 1 272 594 describes the use of friction modifiers, which are the reaction products of certain natural or synthetic carboxylic acid glyceryl esters and alkanol amines in combination with a detergent additive in gasoline for improving the delivery of the friction modifier to the lubricant of the engine. The reaction of preparing the friction modifier is performed without applying a specific temperature profile. The specific selection of a significant molar excess of the alkanol amine is neither suggested nor exemplified. Similar friction modifiers are disclosed in WO 2007/053787, where it is suggested to use the same in combination with a solvent, an alcohol and certain compatibilizer to form fuel additive concentrates remaining fluid at −8° C. or below.
Surprisingly, it has been found possible to modify the preparation of alkanol amine derivatives in such a way that the resulting derivatives provide significant benefits, such as fuel economy benefits and improvements in terms of lubricity, when incorporated in functional fluids employed in internal combustion engines. It has additionally been found that these benefits may be further improved by the incorporation of an additional detergent additive.